WASHINGTON — U.S. long-term mortgage rates were little changed this week. The key 30-year, fixed-rate loan hovered around an average 3.8% for the third straight week.

Before leveling off, rates marked six straight weeks of declines putting them at historically low levels during this spring’s homebuying season. Mortgage buyer Freddie Mac said Thursday the average rate on the benchmark 30-year mortgage ticked up this week to 3.84% from 3.82% last week. By contrast, a year ago the rate stood at 4.57%.

The average rate for 15-year, fixed-rate home loans slipped this week to 3.25% from 3.26%.

The declining rates have been a boon to potential purchasers during this season, and the number of prospective buyers seeking mortgages has increased in recent weeks.

Freddie Mac surveys lenders across the country between Monday and Wednesday each week to compile its mortgage rate figures.

The average doesn’t include extra fees, known as points, which most borrowers must pay to get the lowest rates.

The average fee on 30-year fixed-rate mortgages fell to 0.5 point this week from 0.6 point.

The average fee for the 15-year mortgage declined to 0.4 point from 0.5 point.

The average rate for five-year adjustable-rate mortgages dipped to 3.48% from 3.51% last week.